OK this is what I figured out. If there's a easier/better way to do it please let me know.
1. Create a directory folder on your site (I called my sighup)
2. Create a file named index.html inside it.
3. Paste the following code into your html doc and replace the links
4. Now you can redirect the mobile user to the mobile a specific page and desktop user to a desktop page.
<head>
<script type="text/javascript">
<!--
if (screen.width <= 699) {
document.location = "
www.link-to-mobile-version.html";
}
//-->
</script>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta http-equiv="refresh" content="0;URL=
www.link-to-desktop-version">
<title>Your site name</title>
</head>
<body>
</body>
</html>
